Manchester United's attempt to seal a record 19th league title this weekend has been preceded by another summons for Sir Alex Ferguson from the Football Association's disciplinary arm because of his habit of talking himself into trouble when it comes to referees.

As Ferguson prepares to take his side to Blackburn Rovers on Saturday, needing only a point to return the Premier League title to Old Trafford, the United manager was also contemplating his sixth FA charge in five years for comments he has made about, or to, referees.

The difference this time is that it was not Ferguson castigating one of the Premier League's match officials but talking up Howard Webb as "definitely the best referee in the country" two days before the game against Chelsea last weekend.

Ferguson, citing United's previous controversies against Chelsea, went on to say his "biggest fear" was being the victim of a poor refereeing decision, but that "we are getting the best referee and we hope it's our turn for a little bit of luck".

As the Guardian revealed last weekend, Ferguson was going against the FA's guidelines, installed as part of the Respect campaign, not to say anything before matches that could be construed as trying to influence referees.

The FA's disciplinary department has studied his comments and decided that he has broken rule E3. Ferguson, who has just served a five-match touchline ban for his criticisms of Martin Atkinson after the 2-1 defeat to Chelsea at Stamford Bridge in March, has been charged with improper conduct and has until 4pm on Monday to plead guilty or decide to fight the matter.

Ferguson is the first Premier League manager to be charged with such an offence, which will only heighten the sense within Old Trafford that the FA tends to treat other clubs more leniently.

There is also a feeling of bemusement that a manager should be charged with complimenting a referee when, after matches, others frequently get away with being critical of them.

However, Ferguson would have been aware of the rules and the FA's desire to implement them and it is unlikely it will be seen as a credible defence that he was merely answering journalists' questions. The most likely form of punishment is a fine.

The announcement from FA headquarters came directly after Ferguson's weekly press briefing, meaning he has yet to offer any form of public response, but there is also a depth of bad feeling at Old Trafford that it has, temporarily at least, taken the emphasis off the potential achievement of the club overtaking Liverpool as the most successful league team in the country.

"I said last year that, because of the history of this club, it would happen at some point," Ferguson said, reflecting on the position 20 years ago when the title count was 18-7 in favour of the Merseyside club.

"There is a good structure to our club, we still produce young players really well, our scouting is good and I thought it would happen, whether it was this year, next year or in 10 years' time. The history and capability of the club would always have given us a chance."

Ferguson, nonetheless, anticipates Liverpool could re-establish themselves as a top-four side next season now that Kenny Dalglish has become manager on a permanent basis.

"Liverpool will be galvanised next season. Kenny has signed a three-year contract that settles the club down and I am sure there will be plans to add to that. It just makes it more interesting next year. It has become tighter and tighter."

Ferguson is planning to rest the goalkeeper Edwin van der Sar against Blackburn but said it would otherwise be a near full-strength side.

On the brink of his 12th championship, the manager said he could "understand the disappointment" of the league title being decided on the same day as the FA Cup final between Manchester City and Stoke City because "the final was always a day on its own".

He was also asked whether it would be good for Manchester if both trophies could be won. "I am only interested in ourselves," he said. "I don't care what happens down there."